Lock

Abstract

A lock has improved protection against lock picking. The lock comprises plural tumblers, each generally cylindrical in form with outer and inner circumferential edges, all the tumbles arranged on a common axis. The outer circumferential edge of each tumbler having a single true gate, including a void extending a predetermined distance toward the axis and plural false gates, each having a void of lesser extent. Ridges separates the true gate from adjacent false gates, and separate adjacent false gated from each other. The lock also includes a sheath contacting the inner circumferential edges of the tumblers. The sheath includes ridges located to maintain the tumblers in contact with each other.

What is claimed is: 
     
       1. A lock comprising:
 a plurality of tumblers, each of cylindrical form having first and second faces generally parallel to each other, the tumblers arranged linearly along a common axis, each of the tumblers having inner and outer circumferential surfaces, said outer circumferential surface including an outer circumferential edge; 
 each of the tumblers including a plurality of distinct spaced outer circumferential edge locations, each of said outer circumferential edge locations occupying a different portion of the tumbler outer circumference and each adjacent to at least one other of said locations, 
 said plural distinct locations of each tumbler including a single location comprising an outer circumferential void in a specified portion of the outer circumference extending a prescribed distance from said circumferential edge toward the axis, each said tumbler further including a plurality of other distinct locations representing a void in each of the other distinct locations extending less than said prescribed distance toward said axis, 
 each of the tumblers also including a user tab, 
 each of the tumblers also including a hub on the first face of the tumbler and a recess on the second face of the tumbler, the hub of one tumbler engaging a recess of an adjacent tumbler, the hub and recess of each tumbler defining the inner circumferential surface, 
 a housing surrounding the plural tumblers, having an axis in common with the axis of the tumblers and having openings in the housing, each opening arranged to accommodate a different one of the tumbler user tabs, 
 a spring biased comb located within said housing and urged by said spring in a first direction, said comb extending generally parallel to the common axis and having a plurality of teeth, equal in number to the number of tumblers, said teeth spaced by a distance equal to the distance between adjacent tumblers, said comb supported for movement parallel to said axis, each of said teeth extending toward said axis, each said tooth having a length allowing said tooth to pass by said single location but not pass by any of said other distinct locations of any tumbler, and 
 a sheath having a cylindrical form located within said housing and contacting all said tumblers at said inner circumferential edges. 
 
     
     
       2. The lock of  claim 1  wherein the user tab of each tumbler is located distant from the single location. 
     
     
       3. The lock of  claim 2  wherein said comb includes a locking tab, and which lock further includes a knob supported colinear with said axis and journaled for rotation about said axis and having a recess for accepting said comb locking tab. 
     
     
       4. The lock of  claim 1  wherein said sheath includes a plurality of circumferentially extending ridges, generally parallel to each other and spaced apart so adjacent ridges contact a single tumbler. 
     
     
       5. The lock of  claim 1  wherein said sheath includes an outer surface, said outer surface including a plurality of circumferentially extending ridges, at least one said ridge parallel to another said ridge and spaced to surround a tumbler at an inner circumferential surface of said tumbler. 
     
     
       6. The lock of  claim 5  wherein the sheath includes a first and second end, circumferentially extending ridges located at said first and second ends engaged with inner circumferential surfaces of different ones of said tumblers. 
     
     
       7. The lock of  claim 1  wherein said circumferential void of said single location includes a circumferential segment at said prescribed distance, each of said other distinct locations including at least one segment at less than said prescribed distance from said circumferential edge toward said axis. 
     
     
       8. The lock of  claim 7  wherein at least some of said other distinct locations include plural segments, each said segment of said other distinct locations located a different distance from said circumferential edge, all said different distances less than said prescribed distance. 
     
     
       9. The lock of  claim 1  wherein each of said outer circumferential edge locations is separated from another of said outer circumferential edge locations by an upstanding rib directed radially outward from said axis. 
     
     
       10. The lock of  claim 9  wherein said sheath includes a plurality of circumferentially extending ridges, generally parallel to each other and spaced apart so adjacent ridges contact a single tumbler. 
     
     
       11. The lock of  claim 9  wherein said sheath includes an outer surface, said outer surface including a plurality of circumferentially extending ridges, at least one said ridge parallel to another said ridge and spaced to surround a tumbler at an inner circumferential surface of said tumbler. 
     
     
       12. The lock of  claim 9  wherein the sheath includes a first and second end, circumferentially extending ridges located at said first and second ends engaged with inner circumferential surfaces of different ones of said tumblers.